RPP lets a select group of nonviolent pregnant inmates keep and care for their infants in a separate part of the prison that resembles a dorm. The program is available to women who have 30 months or less to serve after they give birth, so the babies and toddlers who live at the prison full-time are all under 2 1/2 years old.

The notion of infants spending the first part of their lives in prison undeniably sad. While Hanna-Truscott's pictures capture sweet moments, it's clear these infants and toddlers are in an institution and not a home.

Yet supporters of the program would probably argue that it is better for kids to be with their mother in prison than on the outside, where they could end up in foster care or bouncing around various family members' homes. That could interfere with the babies' ability to form secure attachments to their primary caregivers (often the moms). Psychologists have found these early attachments are important for brain growth and the ability to form relationships later on.

So, while the images of kids in prison may be unsettling, the program in Washington State may give these kids the best shot they have. Most women's prisons in the U.S. don't have nursery programs like this one, but they may want to consider implementing them in light of the skyrocketing population of women in prison. The number of women serving sentences of more than a year grew by 757% between 1977 and and 2004, according to the Institute on Women & Criminal Justice. (The male population increased by 388% during that period.)

Pregnant prisoners are a particularly invisible population, Hanna-Truscott noted. "I feel like this is a group of people who don't get a lot of attention," Hanna-Truscott told me. "They're put behind prison walls, and they're pregnant. How vulnerable can you be?"

Hanna-Truscott posted some touching interviews with some of the women at the facility, which reveal how scary it can be to be pregnant and heading to prison.

“When I found out I was pregnant and going to prison, I just cried," one woman, whose name wasn't used, told Hanna-Truscott. "I didn’t know about this program and I was supposed to get eighteen months, so I thought, 'I’m going to have my baby and I’m going to be away from my baby for a year.'”

Then she found out about the residential parenting program, and she got accepted.

"Other inmates said I wouldn’t get in because of my criminal history. But, I don’t have a violent history," she said, "The judge gave me a year and a day and wished me luck. God or somebody is looking after me.”